The currently available commercial bleaches are mainly divided into chlorine bleaches and oxygen bleaches.
In GB Patent No. 2,229,460, a chlorine bleach comprising sodium hypochlorite as a main ingredient is disclosed. The chlorine bleach has a strong bleaching ability, but it has drawbacks that it discolors colored clothes and destroys a textile structure. Further, it has a defect of generating an unpleasant odor due to the presence of chlorine which is known harmful to human body.
Accordingly, the use of oxygen bleaches without the aforementioned drawbacks of the chlorine bleaches has been on the growing increase in recent years. The oxygen bleaches are divided into liquid bleaches and powder bleaches according to its form.
Most of the oxygen bleaches at current markets are powder bleaches which use sodium carbonate peroxyhydrate or sodium perborate, but they have a drawback that they are hardly soluble in water at room temperature, especially in cold water. Further, they are hardly miscible with each solid ingredient homogeneously in the preparation of the powder bleach and also generate dust and are unable to perform partial bleachings on stains.
Therefore, consumers prefer a liquid bleach to powder one due to the convenience to use. For liquid bleach, there are several advantages such as easy weighing, quick dissolving in water, no dust generation and no caking which incurs often in powder bleach during storage.
In U.S. Pat. Nos. 6,235,699, 5,929,012, and 4,900, 468, the liquid bleaches using hydrogen peroxide are disclosed. The liquid bleaches using hydrogen peroxide have some problems such as container expansion and bleaching ability decrease due to the decomposition of hydrogen peroxide during the storage thereof. In addition, it is necessary to keep the pH thereof acidic to stabilize hydrogen peroxide, but bleaching and cleaning ability show a substantial decrease in a low pH condition.
In U.S. Pat. Nos. 3,499,844 and 4,130,501, the method to increase the viscosity of the cleaning composition for improving the chemical stability of the liquid bleach is disclosed. However, the method has some problems that the bleaching and cleaning ability decrease substantially under the acidic pH and the viscosity of the composition changes due to the decomposition of hydrogen peroxide during the storage, which makes its commercialization difficult.